Contents

Executive Summary

As part of an undergraduate engineering course final project, our team of five students was tasked with reverse engineering a modern hand-held wood router. The procedure was to consist of a complete product dissection including disassembly, reassembly and information documentation. The work effort was divided into phases, each encompassing different procedures within the overall project.

The initial phase consisted of a complete disassembly of the product and accompanying photographs and documentation. This was relatively simple as the unit neatly breaks down to four major components which in turn can be further reduced. Once all components were stripped, identified, and cataloged we turned to the task of analyzing each component while considering various engineering issues relevant to the construction of the item. Once satisfied with the intense scrutiny of each component, the next phase consisting of reassembling the unit was underway. Again, engineering issues such as ergonomics, material performance vs. cost and individual component efficiency were considered with respect to the individual components of the unit. The resulting answers to these issues were documented in the form of the Team's recommendations for improving the product.

Once completely reassembled, the team shifted its efforts to creating a presentation to exhibit its findings. This involved the collection and organization of key information regarding the project and the subsequent development of a PowerPoint presentation. This presentation was to showcase the product itself within the context of engineering in general.

Finally, the last phase of the project involved the production of a technical report containing answers to previously posed questions regarding various aspects of reverse engineering and engineering in general. This report was compiled utilizing the various information collected during the previous phases and was significantly more thorough than the presentation with regard to technical data.

Introduction

Early wood workers exhausted themselves while working with primitive hand tools. Certain tasks were especially difficult and labor intensive and thus required particular endurance and skill. Specifically, the task of hollowing out or “routing” out a section of wood was tedious and involved the use of archaic hand tools such as the hand planar. This device consisted of a narrow blade projecting well beyond its base plate and a broad-based wooden hand plane from which to work the tool. Though the process was tiresome, the tool performed satisfactorily and earned the nickname “Woman’s tooth” due to it’s distinct shape (Wikipedia, 2007).

Fortunately for woodworkers, the emergence of new technologies led to the development of increasingly efficient tools. Shortly after WWI, the first hand-held electric wood routers sprang onto the scene and since have experienced the development of a slue of variant designs.

The subject of our project was a Ryobi P600 laminate trimmer. Though not marketed as a "router" it can be classified as belonging to that family of tools. Its primary function is as a trimmer used in wood working to create intricate grooving and shaping. Its a hand-held, single phase, dual grip unit, and at a mere 2.3 lbs - incredibly portable and versatile. The power house is a an 18 volt DC electric motor with a 26,000 rpm no-load rating which is capable of delivering ample torque necessary for light trimming and routing applications. The light weight of the product is attributed to the almost entirely plastic housing which encases the unit [Ryobi Limited].

The reverse engineering project was conducted by five highly motivated University at Buffalo Mechanical Engineering undergraduates. The team leader of MAE277-Group 11 was John Kostadinov. John organized and planned the work effort as well as oversaw progress of task completion. Next, Tom Consolazio conducted preliminary research as well as developed and delivered the presentation portion of the project. George Stamatros was the project photographer and was instrumental in the disassembly and reassembly phases of the dissection. The third member, Mike Bednarz, gathered crucial data necessary to the production of the report as well as documented various steps of the project. Finally, Anthony Hussak played a key role in collecting and organizing various information necessary for project completion. He also aided the presenter in fact checking and generating an outline for the presentation.

Before Disassembly

As described previously, the router's main function is to create intricate grooving and hollow out sections of material. It's rotating bit is driven by an electric motor which houses a spinning armature. This armature, or rotor, is caused to rotate by an electromagnetic field created by the presence of electricity and magnets (Brain).

Our initial impression of the Ryobi P600 was of a product that might contain numerous small components numbering in the 10-20 rage. However, to our surprise the unit dissembled quite tidily into 2 main components - the motor and housing. This led to our conclusion that the router is essentially an electric motor attached to a spinning bit. In addition, judging by the relatively simple demeanor of the unit we guessed that it was composed of around 4 different materials. In reality, eight different materials are represented within the unit.

The unit can be purchased without a battery as it is a part of Ryobi's "One+" system which is comprised of a suite of tools all of which operate from the same rechargeable battery - which can be purchased separately [Ryobi Limited]. This prevents from purchasing redundant equipment and keeps overall cost down. As such, an operations test could not be performed prior to disassembly. However, an accurate estimation of the tool's operating nature and capacity can be made from the knowledge of routers in general. The rotating bit of a router creates a distinct "whine" which is unique amongst wood working tools.

During Disassembly

The following steps were taken to disassemble the router:

• First we removed the clip-on cover from the router

• Then four Phillips head screws were removed from the bottom of the wood working sub-base via a Phillips head screwdriver

• Next, the two plastic depth adjustment latches and the attached springs were taken out by hand

• A yellow cap on the top of the unit was removed by hand, thus releasing the strap and the attached clip

• With those parts removed, the blue and yellow casing easily separated from one another

• At this stage, thirteen different components were counted

• Next to be disassembled was the yellow translucent base

• For this, we used a Phillips head screwdriver and the provided 5/16” wrench

• The black painted hex nut was removed first using the wrench

• Then the washer and rectangular spacer slid off by hand

• Finally, the metal clasp was left and this was also able to be removed

• All parts removed thus far were located on the transparent cylindrical section of the unit

• Next we examined the transparent base

• To separate this part from the cylindrical section, we removed four Phillips head screws from the base

• Once this was completed, we had obtaines a fully disassembled router base

• Next in line was the plastic housing which encases the motor and associated hardware, it also gives the router it's distinct shape

• Holding the housing together were eight Phillips head screws

• With the screws out, a simple pinch of the retainer tabs was all that was needed to separate the twin housing components

• Inside we found the heart of the operation: the motor

• For fear of compromising the integrity of the unit, we did not disassemble any further

On a scale from 1 to 5, with 1 being easy and 5 being difficult, all of the disassembly steps rated around a 1. There weren't many moving parts that required extensive disassembly and everything that did break down was of basic design making it easy to disassemble. The only tools used were a Phillips head screw driver, and the provided 5/16" wrench.

After Disassembly

With disassembly complete, we began to question the engineering involved in the production of the product and why certain choices were made over others. The necessity of the clip-on cover became an immediate point of scrutiny. However, we quickly learned that it functioned quite well as a storage device by allowing the unit be hung when not in use. Similarly, the nylon strap proved to be quite durable and useful despite the light weight of the router. The two latches that held the cover in place were spring loaded and as such easily slid out of their housing quite easily. At this point, only the yellow and blue plastic cover remained. All of the plastic pieces that were disassembled here were made of ABS injection-molded plastic because it is lightweight and durable. We attributed the different colors to a color scheme the manufacturer (Ryobi) may have developed as a method to ensure product line uniformity. On top of the yellow half was a yellow plastic cap that held the nylon strap in place. Once removed, the strap came undone. We felt that the option of strap/no-strap was a wise engineering and marketing choice as it provides functionality as well as serving as an accessory.

The yellow base was a bit more interesting. It consisted (1) of a transparent cylindrical section which wrapped around the main blue plastic casing and (2) a transparent square base that supported the main bulk of the router. This base was intended to serve as a window from which the operator could monitor the router bit as it cut. There were four screws in the bottom of the base that secured it to the cylindrical section. These were not removed as they were molded within the plastic and removing them would not facilitate further disassembly progress. Located on the upright cylindrical section, was a clasp that could be loosened or tightened to achieve desired depth adjustment. This clasp was fastened by a hex nut, washer, rectangular spacer and a bolt which ran through it. We felt as if the clasp was too cumbersome for the size of the unit and a more efficient configuration would not involve this clasp. Yet another aspect worth noting was the choice of yellow color for the transparent base. We were hard pressed to justify the use of yellow and not a more translucent clear shade. We speculated that yellow was used in order to maintain color consistency within the the rest of the product line.

At this phase, the main housing was examined. This blue ABS plastic housing had rubber grips attached near the trigger to allow for a more comfortable grip when operating the product. We suggested the use of additional dampening devices to limit vibration effects on the user during prolonged use. Extra padding and/or insulation seemed as if it may accomplish this. We also noticed indications of apparent manufacturing standardization with regard to the housing. Our group consented to the idea of developing a certain homogeny within a product line to accommodate any potential future interchangeability and keep manufacturing costs low. The blue twin housing pieces were lined with foam. We hypothesized that this was employed to cushion the motor as well as dampen vibration during operation.

Finally, the last step involved inspecting the motor and switch housing. This housing contained the operating on/off switch and was connected to the motor via insulated copper wires. The 18 volt DC electric motor was kept intact as further disassembly would've surely rendered it inoperable. The motor is responsible for converting electrical energy to mechanical energy via the spinning rotor within it. This is accomplished in part by an electromagnetic field - fed by the electric current of the power supply (in this case 18 volt DC from a battery)and magnets. The armature or "rotor" contains an electromagnet which creates the electromagnetic field when electricity is ran through it. Then it spins as a result of the attraction/repulsion with the magnets located on the inner wall of the motor (Brain).

In conclusion, we felt several alternatives to the current configuration would result in a more practical design. For instance, the blue and yellow cover pieces of the clip-on cover could have easily been integrated into a single piece and thereby saving the use of four screws. Also, despite the convenience of cordless operation, we felt that the unit would benefit from a power cord option. This would allow the user to avoid time restrictions associated with battery use.

Note: When clicking on a picture link to view it, you can click on the picture to reduce the magnification to a reasonable level.

Reassembly Process

Reassembling the router consisted of the exact reverse procedure involved disassembly. Please refer to the disassembly section and data table portion for information regarding these steps.

Final Thoughts

As explained previously, operation of this Ryobi hand trimmer centers on the electric motor. The motor utilizes an electromagnetic field created by electricity and magnets to create mechanical energy in the form of a spinning rotor. This rotor turns a wood working bit which is responsible for delivering cutting action along a desired path. The operator can use the transparent base to help guide the router while performing a cut. This unit is also equipped with a depth adjusting device which allows the user to make precise adjustments to ensure accurate cuts. However useful, this device seemed too cumbersome for the small unit and as such we recommend a simpler less bulky mechanism. To our convenience, the unit reassembled in exact reverse order as disassembly had occurred and required only the simplest of tools to maintain: a Phillips head screwdriver and 5/16” wrench. This allowed us to shift our effort and focus on other issues such as engineering design and ergonomics.

Some additional recommendations include integrating the yellow and blue clip-on cover components into a single piece thereby reducing manufacturing costs. We also suggest the addition of more grip/cushioning to the trigger area to allow the user added comfort during periods of extended use. Finally, the addition of a power cord would be would greatly benefit the unit by extending its versatility. We also determined that hand-held power tool prototypes, could be tested in a virtual environment to forecast their performance in real world applications. This would not only aid engineers in technical analysis but dramatically reduce overhead cost for the company.

Overall, we felt the Ryobi trimmer/router was an practically engineered product requiring little to minor changes. It was our pleasure to have the opportunity to work with the product and learn from it. During the course of this reverse engineering project, MAE277 Group#11 gained a new appreciation for the wood router. No longer shall we take for granted the ease of use of today's wood working tools